Field of the Invention:
The invention relates to a transformer configuration for feeding additional voltage to transmission lines. More specifially, to a transformer configuration having an auxiliary transformer connected in series with a transmission line and supplied with energy by an exciter transformer.
To control the energy flow on an electrical energy transmission line, such as a high-voltage line, so-called diagonal or auxiliary transformer configurations are used as needed. In them, longitudinal and/or transverse voltages or currents of arbitrary phase relationship are coupled into the transmission line.
Such a configuration as a rule includes an auxiliary transformer, connected by at least one of its windings into the transmission line and supplied with energy via an exciter transformer. The two transformers, typically also called a transformer unit, can be connected to one another via a control member, such as a converter or a converter set. Such a configuration is known for instance from Published, Non-Prosecuted German Patent Application DE 43 43 992 A. Such configurations are also known in the literature as UPFCs (unified power flow controllers).
In the configurations known in the prior art, the throughput rating of the total configuration, which is definitive for the dimensions, is the product of the maximum network current multiplied by the maximum additional voltage. In the limit case, in which the current on a parallel, uncontrolled transmission line is equal to zero and the total current flows via the controlled transmission line, the full throughput rating must be brought to bear by the auxiliary transformer.